Tuesday, May 18, 2010

Basic Stamp Surgery


I know it's been a while since I've updated, but between work, running our high school's musical, AP classes and AP tests, I have been working away at it, bit by bit.

These last few months have been the stages where I hit every problem that is possible to hit, like bad cabling, broken servos, unresponsive controller boards, broken drill presses, addressing the bytes sent over the serial connection for each individual servo, the whole programming challenge (of both the microcontroller and the computer program, which are written in two completely different languages), and god knows how much more.

Up until the other day, there had been been no smoke or fire.

However, that just changed. While I was running a diagnostic to see exactly how much amperage the servos were drawing, I had 2 of them stalled, and the whole rig was taking a total of about 4 amps. My mistake was that I had without realizing it, run this current through a conductor on the PCB of the Basic Stamp. It wasn't going through the voltage regulator or any other electronics, it was simply using the conductors on the board to send it out to the servos. Even with only 4 amps, this was too much, and the board went up in a nice cloud of smoke.

All was not lost. It was only a relatively small section of conductor (as soon as I saw smoke, I immediately cut all power to everything, if it had been on much longer, the heat would have gone into the actual IC controller chip, which would have been much worse.) So, with a little bit of probing with a multimeter, I found out exactly what had been obliterated, and with a little bit of creative soldering, I managed to put in a secondary conductor that completely bypasses out the broken one.

Here's some pictures of the fix:







Here's where the actual board got completely smoked.



RIP PCB




But is all hope lost?





I think not



All fixed and ready to go